Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An LM immunocytochemical study has investigated the patterns of staining in turtle retina with monoclonal antibodies to the alpha, beta and gamma isozymes of protein kinase C. The protein kinase C-gamma antibody reveals cells in the ganglion cell layer, occasional amacrine cells and faint banding in strata 2 and 4 of the inner plexiform layer. The protein kinase C-beta antibody stains primarily amacrine cells that have dendrites running in strata 2, in 4 close to the 3/4 border and on the 4/5 border of the inner plexiform layer. Protein kinase C-alpha immunoreactivity is seen in a population of bipolar cells. The latter are characterized by stained axon terminals in strata 3 and 4 of the inner plexiform layer. A type of amacrine cell, different from those seen with the other antibodies, is also immunoreactive to protein kinase C-alpha. EM immunocytochemistry (using a polyclonal antibody) reveals protein kinase C immunoreactivity in photoreceptor cells, bipolar cells, amacrine cells and ganglion cells. In photoreceptors protein kinase C immunoreactivity occurs as patchy staining associated with vesicles and the plasmalemma in pedicles and telodendria. Some varieties of bipolar cell display protein kinase C reaction product throughout the entire cell. Their dendrites contact photoreceptor pedicles at wide-cleft basal junctions and ribbon and non-ribbon related narrow cleft junctions. A few lateral elements per cone or rod pedicle are always protein kinase C-immunoreactive. Amacrine and ganglion cells typically show small clumps of protein kinase C immunoreactivity around vesicles and close to the postsynaptic membranes. Synaptic boutons of some varieties of amacrine cell stain more uniformly. Protein kinase C-immunoreactive bipolar cells are most commonly presynaptic in stratum 4 of the inner plexiform layer, while protein kinase C-immunoreactive amacrine cells are both pre- and postsynaptic throughout strata 1, 2, 3 and 4. Stratum 5 appears to be almost devoid of protein kinase C-immunoreactive neural profiles.
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PMID:Immunocytochemical staining with antibodies against protein kinase C and its isozymes in the turtle retina. 128 73

Effects of insulin and phorbol esters on subcellular distribution of protein kinase C (PKC) isoforms were examined in rat adipocytes. Both agonists provoked rapid decreases in cytosolic, and/or increases in membrane, immunoreactive PKC-alpha, PKC-beta, PKC-gamma, and PKC-epsilon. Effects of phorbol esters on PKC-alpha redistribution to the plasma membrane, however, were much greater than those of insulin. In contrast, insulin, but not phorbol esters, stimulated the translocation of PKC-beta to the plasma membrane, and provoked changes in PKC-zeta redistribution. Neither agonist altered subcellular distribution of PKC-delta, which was detected only in membrane fractions. Our findings indicate that insulin and phorbol esters have overlapping and distinctly different effects on the subcellular redistribution of specific PKC isoforms.
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PMID:Effects of insulin and phorbol esters on subcellular distribution of protein kinase C isoforms in rat adipocytes. 144 77

SH-SY5Y human neuroblastoma cells can be induced to differentiate into a neuronal phenotype by treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). In other cell systems, TPA treatment frequently leads to down-regulation of protein kinase C (PKC). However, we now report that TPA-treated and non-treated SH-SY5Y cells express PKC-alpha, but not PKC-beta and PKC-gamma, mRNA. Furthermore, only a slight down-regulation of the PKC-alpha protein could be seen during prolonged treatment with 16 nM TPA, the concentration giving optimal differentiation. In contrast, a higher concentration of TPA (1.6 microM) results in a poor neuronal differentiation and a complete down-regulation of PKC-alpha. PKC-alpha was rapidly translocated to the particulate fraction and remained membrane bound for at least 4 days during treatment with 16 nM TPA. In such cells a sustained increased level of the phosphorylated form of a 80,000 Dalton PKC-substrate was found. In addition to this sustained augmented phosphorylation, administration of fresh TPA at day 4 caused a small but reproducible further increased level of phosphorylated substrate. When the PKC activity was measured by the histone phosphorylation assay a substantial fraction of the initial enzyme activity could still be detected after 4 days of TPA treatment. Taken together, the data demonstrate that PKC remains functionally active during TPA induced differentiation of SH-SY5Y cells, which may suggest a continuous role for the enzyme during the differentiation process.
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PMID:Protein kinase C remains functionally active during TPA induced neuronal differentiation of SH-SY5Y human neuroblastoma cells. 150 12

Of the recently identified protein kinase C (PKC) types of group B (delta, epsilon, zeta, eta, PKC-L), only PKC-epsilon has been characterized in great detail. In order to compare the regulatory and catalytic properties of these new kinases, we have expressed PKC-delta, -epsilon, -zeta and PKC-L as recombinant proteins from their cDNAs in insect cells via baculovirus vectors and in mammalian COS-1 cells. After expression in insect cells, phorbol ester binding and kinase activities of the group B enzymes were compared with the respective activities of a member of group A, PKC-gamma. Although PKC-delta and PKC-L(eta) bind phorbol ester to a similar or the same extent as PKC-gamma, they show a distinctively different behaviour towards conventional PKC substrates such as histone, myelin basic protein, protamine and protamine sulphate, suggesting either that phorbol esters are not able to fully activate these enzymes or that their substrate specificities are very different from those of the group A enzymes. PKC-zeta, a polypeptide of 80 kDa, does not bind phorbol ester and does not phosphorylate these substrates to a significant extent. Consistent with their ability to bind phorbol ester, recombinant PKC-delta and PKC-epsilon are down-regulated in COS cells by prolonged treatment with phorbol ester, whereas PKC-zeta protein levels remain unaltered.
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PMID:Protein kinase C group B members PKC-delta, -epsilon, -zeta and PKC-L(eta). Comparison of properties of recombinant proteins in vitro and in vivo. 159 Jul 67

The localisation and immunochemical identification of 3 different forms of protein kinase C (PKC-alpha, PKC-beta and PKC-gamma) in retinas of different species were analysed by immunohistochemistry and SDS-PAGE-Western blotting, respectively. Only in some cases was there a correlation between the findings from each procedure. One reason for the lack of correlation could be the small amounts of PKC present in some retinas, which made detection possible only by first concentrating the antigen by SDS-PAGE and then carrying out Western blotting. Another possible reason is that an antibody recognises unknown antigens immunohistochemically, but, because of their specific characteristics, they are denatured when subjected to SDS-PAGE and Western blotting and therefore remain undetected. PKC-beta immunoreactivity is present in rabbit, frog and goldfish retinas but absent from the rat retina. However, SDS-PAGE and Western blotting experiments showed that the PKC-beta isoenzyme is absent from the fish retina but present in the rat retina. PKC-beta immunoreactivity in rabbit retina is present in ganglion and/or amacrine cells; in the frog retina the enzyme is associated with some bipolar cells. In the goldfish retina, PKC-beta is associated with a large population of cells in the ganglion cell layer as well as with some amacrine cell bodies. PKC-alpha is present primarily in bipolar cells of rat, fish and rabbit retinas and was not detected by immunohistochemistry or blotting experiments in the frog retina. SDS-PAGE and Western blotting of retinal extracts from different species showed that PKC-gamma occurs in the rabbit where it was associated with ganglion and/or amacrine cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The occurrence of three isoenzymes of protein kinase C (alpha, beta and gamma) in retinas of different species. 161 8

Regulation of protein kinase C (PKC) isoform mRNAs has been studied in the immature, murine B lymphoma WEHI-231 by the MAPPing protocol and by slot blot analysis of unamplified mRNA. This membrane IgM (mIgM)-positive cell line has been previously used as a model to study signal transduction by mIgM in immature B lymphocytes and the role of those signals in the induction of immune tolerance in the B cell compartment. Stimulation of the cells by anti-mu antibodies, phorbol ester, or Ca2+ ionophore caused growth arrest and death of the cells. IL 4 and IL 5 slowed the growth of the cells. Of these stimuli, only anti-mu stimulation affected PKC mRNA levels. Anti-mu treatment caused a transient decrease in the amount of PKC-zeta isoform mRNA within 3 hr. Within 24 hr levels returned toward normal. Anti-mu had little or no effect on the expression of mRNA for the alpha, beta, delta, or epsilon isoforms of PKC. WEHI-231 cells do not express PKC-gamma. Although anti-mu treatment blocked progression of the cells from the G0/G1 stage into the S phase of cell cycle, viable sort selected cells in either the G0/G1 or the S/G2/M phases showed no clear difference in the expression of PKC-zeta message. Thus, there is not preferential regulation of expression of PKC-zeta during stages of the cell cycle. The results show that mIgM on WEHI-231 cells can transduce a signal that is not mediated by PKC or Ca2+ mobilization alone. The signal causes transient, selective down-regulation of mRNA encoding the zeta PKC isoform.
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PMID:Transient down-regulation of PKC-zeta RNA following crosslinking of membrane IgM on WEHI-231 B lymphoma cells. 162 54

The levels of protein kinase C (PKC) activity, PKC isozymes, as well as the level of endogenous diacylglycerols (DAG) were examined in early emergence mouse skin papillomas and compared to the levels in the epidermis. The papillomas were derived from a two-stage carcinogenesis protocol in which mice were initiated with 7,12-dimethylbenz[a]anthracene (DMBA) and promoted twice weekly for only 12 weeks with 12-O-tetradecanoylphorbol-13-acetate (TPA). As expected, greater than 90% of these early emergence papillomas contained an activated Ha-ras gene with an A----T transversion in the 61st codon. There was a TPA-independent, irreversible decrease in total PKC activity (70%) in the early emergence papillomas compared to that in the epidermis. Immunoblot analysis of epidermis and papillomas taken 4 weeks following the cessation of TPA treatment, a time when PKC catalytic activity has completely recovered to control level in epidermis but not in papillomas, revealed that the levels of PKC-alpha and PKC-beta 2 were dramatically decreased in the cytosol of the papillomas, while the levels of these two isozymes in the particulate fraction were approximately equal to the epidermis. PKC-delta, -epsilon and -zeta immunoreactive proteins were present in both epidermis and papillomas and only minor changes were observed in the papillomas. PKC-delta and PKC-epsilon displayed a particulate fraction localization in both the epidermis and papillomas, while PKC-zeta was found in both subcellular fractions. We were unable to detect PKC-gamma in mouse epidermis or papillomas. Since the level of DAG has been shown to be elevated in some ras-transformed cells, we examined DAG levels in the papillomas, as an increased DAG level could explain the constitutive decreases in the levels of PKC. Measurements of cellular DAG indicated that there was no elevation in the total pool of DAG in the early emergence papillomas. These data demonstrate an irreversible decrease in and alteration of the subcellular distribution of PKC-alpha and beta 2 in DMBA-initiated/TPA-promoted papillomas. These changes are TPA-independent, and occur in the absence of an elevation in the total pool of endogenous DAG. These alterations of PKC isozymes may be important early events in multistage tumorigenesis.
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PMID:Alterations in protein kinase C isozymes alpha and beta 2 in activated Ha-ras containing papillomas in the absence of an increase in diacylglycerol. 163 76

Three monoclonal antibodies (mAb) directed against the regulatory domain of the protein kinase C gamma (PKC gamma); 15G4, 5A2 and 36G9, were shown to display distinct properties with respect to PKC gamma kinase activity [Cazaubon, S., Marais, R., Parker, P. & Strosberg, A.D. (1989) Eur. J. Biochem. 182, 401-406]. The mAb 5A2 and 36G9, which act as potent inhibitors of the cofactor-dependent kinase activity, can no longer bind PKC gamma in the presence of phosphatidylserine and phosphatidylserine/phorbol ester, respectively; 15G4 binding is not influenced by effectors. Due to this functional relationship between the inhibitory mAb- and cofactor-binding sites, we sought to localize the mAb epitopes with respect to the functional sites of PKC gamma. For this purpose, several deletions were introduced at the 5' end of the PKC gamma cDNA and the mutant proteins were expressed in Escherichia coli. The determination of the immunoreactivity of the deleted PKC gamma proteins shows that the amino acid residues essential to the binding of 5A2 and 36G9 are directly adjacent to the second cysteine-rich motif: these are contained in the sequences at positions 151-163 and 164-197, respectively. In addition, various deletions around the C1 region of the regulatory domain allowed the identification of the second cysteine-rich motif as a functional binding site for phorbol dibutyrate. These deletion studies thus demonstrate that the epitopes recognized by the inhibitory mAbs 5A2 and 36G9 are distinct from the cofactor-binding sites. This suggests that the binding of phosphatidylserine and phorbol ester induce conformational changes in the regulatory domain of PKC, which are thus responsible for the loss of the 5A2 and 36G9 immunoreactivity of the native protein. In this conformational state, PKC gamma conserves its ability to interact with the non-inhibitory mAb 15G4. By using synthetic peptides, the 15G4 epitope was localized to the sequence 297-310 in the V3 variable region. This indicates that the flexibility of the V3 region, which delimits the C-terminus of the regulatory domain, may not be necessary for the allosteric activation of PKC. In view of these results, we propose that PKC activation by its cofactors results in intramolecular changes which allow the enzyme to bind exogenous substrates.
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PMID:Effector-dependent conformational changes in protein kinase C gamma through epitope mapping with inhibitory monoclonal antibodies. 170 15

The substrate specificity of purified PKC-alpha, -beta and -gamma has been investigated. A series of synthetic peptides based upon the sequence surrounding serine-7 in glycogen synthase were generated and used to determine the basic residue requirements of these PKC isotypes. While PKC-alpha and -beta are indistinguishable in their phosphorylation of these peptides, PKC-gamma shows a distinct specificity profile for these synthetic substrates.
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PMID:Studies on the primary sequence requirements for PKC-alpha, -beta 1 and -gamma peptide substrates. 170 30

T lymphocyte activation is initiated as a result of the interaction between the TCR complex and Ag as seen in the framework of a membrane-bound MHC molecule. Receptor stimulation results in a rise in free intracellular Ca2+ and the activation of protein kinase C (PKC). Bryostatin (Bryo) and phorbol esters (e.g., 12-O-tetradecanoylphorbol 13-acetate (TPA] are PKC activators with somewhat different immunologic effects. We compared the effect of Bryo and TPA on the T cell tumor line Jurkat and derivatives of Jurkat cells grown in media supplemented with 100 nM Bryo ("BR100" cells) or 100 nM TPA ("TP100" cells). In untreated Jurkat cells, there is a dose- and time-dependent decrease in proliferation, compared to media controls, after the administration of as little as 10 nM TPA. This can be reversed in a dose- and time-dependent manner by Bryo. Interestingly, the expression of the transferrin receptor parallelled this effect on proliferation. Furthermore, Jurkat cells grown continuously in 100 nM TPA regained full proliferative capacity after several weeks in culture and transferrin receptor expression returned to near the level seen in untreated Jurkat cells. The chromatographic separation of PKC activity in these three cell lines showed that total PKC activity was dramatically decreased in both the TP100 and BR100 cells when compared to untreated Jurkat cells. However, in the TP100 cells there exists a peak of activity that is activated by Bryo, but not TPA. Western blots of whole cell lysates of the three cell lines showed that PKC-alpha and PKC-beta II were both down-regulated in BR100 and TP100 cells compared to untreated Jurkat cells. PKC-gamma was not detected in any of the cell lines. Therefore, the Bryo-specific peak seen in TP100 cells may be PKC-delta, -epsilon, -zeta, -eta, or a novel PKC isoform. This could provide the basis for a molecular characterization of the differences in PKC activation between phorbol esters and Bryo.
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PMID:Response of Jurkat T cells to phorbol ester and bryostatin. Development of sublines with distinct functional responses and changes in protein kinase C activity. 183 42


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